> am i gonna break things badly?
Maybe, maybe not, but just changing that #define won't have the effect
you want, since there's a bit of machine-dependent code which needs to
be whacked, as well.
In PR 1891 (see http://www.NetBSD.org/cgi-bin/query-full-pr?1891) I
proposed a set of diffs to make having a variable-sied and larger
message buffer easier. They don't actually make message buffer size a
configurable option on the x86, but it's pretty clear looking at the
diffs how to make the message buffer larger.
Anyway, it might be an interesting starting point for you.
chris